The trunking communication system originated in the late 70s and the early 80s of 20th Century. The earliest trunking communication is an analog system, while the digital trunking technology appeared worldwide in the 90s of 20th Century. In the late 90s of 20th Century, the digital trunking technology appeared in China. One service of the trunking communication can include a plurality of users being allocated into different groups, each of which is called a trunking group. One of the most primary features of the trunking communication is trunking call or group call. The group call function of the trunking service is to call a group number at one communication terminal or a dispatching station, so that all the terminals in the group can be simultaneously called into one call so as to realize an effect that a plurality of users communicate at the same time.
The trunking communication system generally uses a group call identifier to identify one trunking group, and the group call identifier uniquely identify one trunking group, and generally may be consisted of a group identifier (GID or Gid) solely or together with other attributes such as the group call area, wherein the GID identifies the terminal in the trunking group, and each terminal of the trunking group has the group ID defined by the trunking group, and the trunking group stores the group ID in a data store device on the system side and in the terminal, which is used to determine the trunking group to which the terminal belongs when authentication is performed. One terminal may sign up with a plurality of trunking groups at the same time. The group call area is an area that the trunking group may call defined when the group call of the trunking group is a voice group call service. Only the terminal which is located in this area and is a member of the trunking group can perform a call service. Since the GID is used to identify the trunking group to which the terminal belongs, each different trunking group has a different GID, but the resource of the GID is limited, for example, a 3-digit GID number can identify 1000 different trunking groups, while a 4-digit GID number can identify 10000 different trunking groups. However, as the scale-up of the trunking network, such an encoding mode of the GID is far from enough in view of the trunking communication system in the whole communication network, which will result in that a group paging operation cannot be performed effectively. Further, it will result in inconvenience in management if this encoding mode of the GID is used and the number of digits for encoding the GID is increased to follow the development of the trunking communication system.